8.2Low or zero carbon technologies

This chapter gives guidance on meeting the Technical Requirements for low or zero carbon (LZC) technologies.


This chapter provides guidance on low or zero carbon (LZC) technologies acceptable to NHBC. Other systems that follow the general principles of this chapter may also be acceptable, subject to specific agreement with NHBC.

Additional requirements for solid fuel and oil fired boilers are given in Chapter 6.8 ‘Fireplaces, chimneys and flues’. Guidance on other internal services is given in Chapter 8.1 ‘Internal services’.

This chapter provides guidance on the following technologies:

The illustrations provided within the introduction are generic and do not indicate the only possible systems acceptable to NHBC.

Definitions for this chapter

ControlsControls are used to operate and/or regulate the system and may be electrical or mechanical.
Exclusion zoneAn area where entry is restricted during periods when maintenance is in progress, to prevent risk of injury or loss of life.
Ground collectorsThe component of a ground source heat pump system which absorbs heat from the ground. Collectors can be installed either horizontally or vertically in the ground. They may also be incorporated into proprietary foundation systems.
Interstitial condensation Condensation caused by vapour from within the building condensing on colder surfaces within the wall construction, often occurring due to cold bridging.
InverterA device that converts direct current into alternating current.
Islanding (island mode operation) Where an LZC technology feeds the network or local distribution system during a planned or unscheduled loss of mains supply.
Low or zero carbon (LZC) technologiesA term applied to renewable sources of energy, and also to technologies which are significantly more efficient than traditional solutions, or which emit less carbon in providing heating, cooling or power.
Open loop
system stem
A heat pump system that extracts water from an underground source, pumps it through a heat exchanger and returns it underground.
Parallel electrical generationA system in which building loads can be fed simultaneously from the national grid or electricity supply grid and on-site sources such as wind turbines and photovoltaic panels.
PerformanceThe manner or quality of functioning for a material, product or system.
Refrigerant pipeworkCarries refrigerant between the indoor and outdoor unit of a split system. Normally made of copper and must be insulated and protected from damage.
Renewable energyEnergy from naturally available sources that can be replenished, including energy from the sun, the wind and tides, and from replaceable matter such as wood or other plant material.
Split systemA type of heat pump in which the condenser is located indoors, the evaporator is located outdoors, and the two are linked by refrigerant pipework.
SwitchgearThe combination of electrical switches, fuses and/or circuit breakers used to isolate electrical equipment.